Problem: Solve for $n$ : $n - 11 = -13$
Add $11$ to both sides: $ \begin{eqnarray} \\ n - 11 &=& -13 \\ \\ {+11} && {+11} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{-11 + n} &\hphantom{=}& \hphantom{-13} \\ n &=& -13 {+ 11} \\ \end{eqnarray} $ Simplify. $ n = -2$